1. Field of the Invention
The present invention relates to an image forming apparatus in which a high-frequency magnetic field is generated from a coil and is applied to a heat generation member to cause the heat generation member to generate eddy currents, and a developer image on a recording medium is fixed by self-heat-generation of the heat generation member based on loss of the eddy currents.
2. Description of the Related Art
In an image forming apparatus which is a so-called electronic copying machine using digital technology, an original document table on which an original document is set is exposed to light, to obtain image signals corresponding to amounts of reflected light from the original document table by means of a line sensor of a CCD (Charge-Couple Device) type, and laser light corresponding to the obtained image signals is irradiated on a photosensitive drum, to form an electrostatic latent image on the circumferential surface of the photosensitive drum. The electrostatic latent image is developed by sticking a developer agent (toner) previously changed (to negative) polarity. A paper sheet is fed at a timing in compliance with the rotation of the photosensitive drum, and the developed image (developer image) on the photosensitive drum is transferred to the sheet. The paper sheet to which the developer image has been thus transferred is further fed to a fixing device.
The fixing device comprises a heat roller and a press roller in contact with the heat roller. A paper sheet is inserted between both rollers. The developer image on the paper sheet is fixed by the heat of the heat roller while conveying the paper sheet.
An example of a heat source for the heat roller is an induction heating device. The induction heating device comprises a coil contained inside the heat roller, and a high-frequency generation circuit which supplies the coil with a high-frequency current.
The high-frequency generation circuit comprises a rectifier circuit for rectifying the voltage of an alternative power source, a switching circuit for converting an output voltage (direct current voltage) of the rectifier circuit into a high frequency wave having a predetermined frequency. The coil is connected to an output end (the output end of the switching circuit) of the high-frequency generation circuit.
When the high-frequency generation circuit operates, the coil is supplied with a high-frequency current, so that a high-frequency magnetic field is generated from the coil. This high-frequency magnetic field is applied to the heat roller, so that eddy currents are generated from the heat roller. Further, the heat roller autonomously generates heat, based on the loss of the eddy currents, and the developer image on the paper sheet is fixed by the generated heat.
In the electronic copying machine described above, however, when start-up processing is executed at the time of turning-on of the power, starting -of the induction heating device takes longer than the other parts.
It is conventionally arranged such that start-up of the induction heating device is started after the other parts have been started-up.
Therefore, there is a problem that warm-up takes a long time.
The present invention has been made in consideration of the above situation and has an object of shortening the warm-up time.
An image forming apparatus according to the present invention has a fixing device which includes a coil in a heat roller and lets the heat roller generate a high-frequency magnetic field thereby to generate eddy currents from the heat roller, and which fixes a developer image on to a recording medium by autonomous heat generation of the heat roller, based on eddy current loss, comprising: drive means for driving the fixing device; and execution means for executing, preceding start-up processing, to start drive of the fixing device by the drive means prior to other parts.
An image forming apparatus according to the present invention has a fixing device which includes a coil in a heat roller and lets the heat roller generate a high-frequency magnetic field thereby to generate eddy currents from the heat roller, and which fixes a developer image on to a recording medium by autonomous heat generation of the heat roller, based on eddy current loss, comprising: drive means for driving the fixing device; execution means for executing preceding start-up processing, to start drive of the fixing device by the drive means prior to other parts; determination means for determining an abnormality of the fixing device; and stop means for stopping the preceding start-up processing by the execution means, when an abnormality of the fixing device is determined by the determination means.
An image forming apparatus according to the present invention has a fixing device which includes a coil in a heat roller and lets the heat roller generate a high-frequency magnetic field thereby to generate eddy currents from the heat roller, and which fixes a developer image onto a recording medium by autonomous heat generation of the heat roller, based on eddy current loss, characterized by comprising: drive means for driving the fixing device; execution means for executing preceding start-up processing, to start drive of the fixing device by the drive means prior to other parts; setting means for setting a service mode for performing maintenance on the image forming apparatus; and stop means for stopping the preceding start-up processing by the execution means, when the service mode is set by the setting means.
In an image forming apparatus according to the present invention, an image is formed on an image carrier, the image of the image carrier is developed with a developer agent, this developer image is transferred to a transfer medium, and thereafter, the developer image is fixed by a fixing device using induction heating, and the apparatus comprises: first control means for driving and controlling the fixing device which performs the fixing by the induction heating; and second control means for controlling the entire image forming apparatus, wherein the first control means and the second control means are provided independently from each other, and start of drive/control of the fixing device by the first control means and start of drive/control, by the second control means, of parts other than the fixing device are carried out in parallel at the time of turning on a power source.
In an image forming apparatus according to the present invention, an image is formed on an image carrier, the image of the image carrier is developed with a developer agent, this developed image is transferred to a transfer medium, and thereafter, the developed image is fixed by a fixing device using induction heating, and the apparatus comprises: first control means for driving and controlling the fixing device which performs the fixing by the induction heating; and second control means for controlling the entire image forming apparatus, wherein after drive/control of the fixing device by the first control means is started at a time of turning on a power source, drive/control of parts other than the fixing device is started by the second control means.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.